Effects of chelating agents on distribution and excretion of terbium in mice

When terbium chloride (TbCl(3)) was intravenously injected into mice, terbium (Tb) was mainly distributed into the spleen, lung, and liver. Thus, the effects of five chelating agents on the distribution of Tb to the spleen, lung, and liver of mice were examined. The treatments with diethyldithiocarbamate (DDTC), N-p-methoxybenzyl-D-glucamine dithiocarbamate (MeOBGD) and 2,3-dimercaptopropanol (BAL) reduced the content of Tb in the spleen. The treatments with D-penicillamine (D-PEN), ethylenediaminetetraacetic acid (EDTA), and MeOBGD reduced the content of Tb in the lung. However, BAL treatment enhanced the content of Tb in the lung, indicating the redistribution of Tb to the tissue. Although the biliary excretion of Tb was significantly increased in mice treated with EDTA and MeOBGD, these increases were negligibly small, and the metal was not detected in the urine. These results indicate that well-known chelating agents such as D-PEN, EDTA, DDTC, MeOBGD, and BAL have little ability to excrete Tb into the bile and urine. Further studies are necessary to develop a new type of chelating agent to remove Tb effectively from the body.